Recent studies have found that eating a greater variety, but not a greater quantity, of fruit significantly reduces the risk for Type 2 diabetes. This made researchers wonder whether some fruits might have a stronger effect than others.

Using data from three large health studies, they tracked diet and disease prospectively over a 12-year period in more than 185,000 people, of whom 12,198 developed Type 2 diabetes. The analysis appears online in BMJ.

After controlling for many health and behavioral factors, researchers found that some fruits — strawberries, oranges, peaches, plums and apricots — had no significant effect on the risk for Type 2 diabetes. But eating grapes, apples and grapefruit all significantly reduced the risk. The big winner: blueberries. Eating one to three servings a month decreased the risk by about 11 percent, and having five servings a week reduced it by 26 percent.

“Increasing whole fruit consumption, especially blueberries, apples and grapes, is important,” said Dr. Qi Sun, an assistant professor of medicine at Harvard and the senior author of the study. “But I don’t want to leave the impression that fruit is magic. An overall healthy lifestyle is essential too.”